There was a letter in the Washington Post last week about group grading. The parent writing the letter was concerned that her child seems to be the one continually saddled with leading things while the hangers-on benefit from her diligence. Hey---we've all been that kid's shoes, but that doesn't make it okay for this classroom practice to continue.
In the reply, it is noted that for that particular district, it is policy that "Grades must be based on individual demonstration of skill and understanding."; however, it is unlikely that group grading has gone the way of the dodo bird. Why? "Teachers will be less likely to say they are giving grades for group work, but the ones I know have found that, for some students, cooperative projects reveal important skills, such as imagination, leadership and bargaining, for which their final grades will look better than they might otherwise have."
What a crock. The information described there is about behaviors---not learning. (And how exactly does one score "imagination, leadership, and bargaining"?) Even if group grades were acceptable, you will still need to base your evidence on learning targets in order to make a valid judgment.
We know from educational research that cooperative learning experiences can be valuable to students. But, as the name suggests, these strategies are to be used while learning---not for assessment. One would hope that school districts are being vigilant about this sort of practice. We owe it to students and their families to give them the best information possible about individual progress and performance.